The present invention is a hydrosilation process where a silicon hydride is reacted with an unsaturated reactant in the presence of a platinum catalyst and an accelerator selected from a group consisting of tertiary alcohols, silated tertiary alcohols, benzyl alcohol and silated benzyl alcohol. The accelerators are especially useful for the hydrosilation of unsaturated reactants where the unsaturation is in the internal portion of the reactant's structure, for example, as in cyclopentene and cyclohexene. The accelerators are believed to be effective in the presence or absence of oxygen.
It is known in the art to produce organosilicon compounds by reacting a silicon hydride containing compound with an unsaturated organic compound in the presence of a catalyst. This reaction is typically referred to as hydrosilation or hydrosilylation. Typically the catalyst is platinum metal on a support, a platinum compound generally in a solvent, or a platinum complex.
In Speier et al., U.S. Pat. No. 2,823,218, a method for the production of organosilicon compounds by reacting an Si-H with a compound containing aliphatic carbon atoms linked by multiple bonds in the presence of chloroplatinic acid is taught. Lamoreaux, U.S. Pat. No. 3,220,972, teaches a similar process, however the catalyst is a reaction product of chloroplatinic acid.
One of the major problems known in the art with hydrosilation reactions is the de-activation of the catalyst prior to the completion of the reaction. One method for reactivation of the catalyst has been to expose the reaction mixture to oxygen. For example, Onopchenko et al., U.S. Pat. No. 4,578,497, teach the use of an oxygenated platinum containing catalyst for use in hydrosilating alkylsilanes. Kleyer et al., U.S. Pat. No. 5,359,111, disclose a method for controlling hydrosilation reaction mixtures by controlling the solution concentration of oxygen in the reaction mixture, relative to the platinum present in the reaction mixture.
In addition to the problem of de-activation of the platinum catalyst, hydrosilation processes taught in the art are not particularly effective in hydrosilating internal unsaturated bonds in organic molecules. The present inventors have unexpectedly discovered that tertiary alcohols, silated tertiary alcohols, benzyl alcohol, and silated benzyl alcohol can act as accelerators for platinum catalyzed hydrosilation processes. The accelerators are believed to improve yield of the process in the presence or absence of oxygen and are particularly effective in facilitating the hydrosilation of internal unsaturated bonds of organic molecules.
Bank et al., U.S. application Ser. No. 08/329,819, describe the use of unsaturated ketones as accelerators for hydrosilation.